Integrated circuit (“IC”) packages are ubiquitous in modern electronic devices. A typical integrated circuit package includes an IC die (“chip”) that is mounted on a substrate such as a lead frame. The die and portions of the substrate are usually covered in a layer of protective encapsulant. An IC die is a small block of semiconductor material, such as silicon, in which an electrical circuit that performs a predetermined function is provided. Some dies have contact pads on a top surface that allow the die circuit to be connected to the substrate or other electrical components by wire bonding. Another type of die known as a flipchip has an array of conductive solder balls formed on a bottom surface of the die. The solder balls are connected to corresponding contact pads of a substrate on which the die is mounted.
In some cases it may be desirable to add functionality to an IC die by attaching one or more discrete circuit components to an integrated circuit package that contains the die. The discrete components may be passive circuit elements, e.g., capacitors, inductors, and resistors. Or, the discrete components may be more complex circuit devices such as, for example, transistors, crystals, sensors, microelectromechanical system (MEMS), or oscillators. A discrete component is typically provided in a small hard surfaced package that may have various shapes, heights and sizes. Two or more electrical contacts, such as contact pads, or leads, may be provided for attaching the discrete component to corresponding electrical contacts on a die, substrate or other electrical component. The phrase “discrete component” as used herein means the primary circuitry of the component and packaging thereof. The phrase “discrete component assembly,” as used herein, means the discrete component and any structure used to attach it to an electrical substrate and any electrical conductors/contacts that are provided to electrically connect the discrete component to an electrical substrate or other electrical components.
After attaching the die and discrete component(s) a layer of protective encapsulant is often applied to complete an IC package. The encapsulant usually covers the die, discrete component(s) and at least portions of the substrate. Some complex packages have multiple IC dies and multiple discrete components and are often referred to as “systems in package modules.” The phrase “integrated circuit (IC) package” as used in this specification means any functional assembly that includes an IC die mounted on a substrate, including systems in package modules as well as simple die substrate assemblies, whether encapsulated or not.
There is a continuing need for manufacturers to decrease the size, and particularly the height, of IC packages to facilitate the production of ever smaller electronic devices, such as cell phones, tablet computers and smart appliances.